Matrix lamp bank displays are widely used for promotional and informational purposes along roads, inside and outside of buildings, and in sports facilities. They can display written announcements, information, and graphic images. Both the written and graphic presentations can be either static or moving.
Like television, the first matrix lamp bank displays exhibited black and white presentations achieved by simply turning white incandescent lamps on or off at selected locations or "pixels" about the matrix. While these lamp bank displays are still widely used, there is a growing desire to present colored images, paralleling the widespread adoption of color in television motion pictures, printing and other forms of visual and graphic art.
One way to achieve a color matrix lamp bank display is to utilize cathode ray tubes capable of projecting multiple colors in various shades of grey. Such matrix displays are used for "instant replay" video presentations, typically in large sports facilities. Their utilization is limited by the extreme cost of such an installation.
A less-expensive form of matrix color display can be achieved by grouping multiple light sources adjacent to one another to present the primary colors (typically 4 - white, red, blue and green). The group of lamps is then activated in the same manner as the individual lamps in a simple black and white matrix, selecting the primary colors desired for the color presentation of each grouped area. At the present, this has been accomplished by using colored light sources, selecting lamps of the color or combination of colors required at each group of lamps. Any cover or lens over these lamps has been of a common tint, typically clear so as to avoid any modification of the lamp color when viewed from the exterior of the display.
Colored incandescent lamp bulbs are substantially more expensive to install and maintain, when compared to the installation and upkeep of matrix lamp bank displays using white lamps. Maintenance of a color lamp bank display requires an inventory of four different lamps. The installation or replacement lamps risks the possibility that a lamp of the wrong color will be placed within a group. To resolve these difficulties, and to reduce the initial and continuing costs relating to a color matrix lamp bank display, the present invention was developed, using a common white lamp as a light source and interchangeable light filtering assemblies placed forward of each lamp. This not only allows for use of inexpensive lamps, it also permits replacement of all lamps from a single lamp inventory. It allows for greater light balance between the selected colors by incorporating such balance into the lens design, thereby eliminating light variations in color and intensity due to lamp construction and age.
Another object of this invention is to provide a covering lens system that permits access to each lamp from the front of the display, making lamp replacement much easier than in earlier installations where lamp access was only available from the rear. The light filtering assemblies are designed to accommodate wide temperature fluctuations that typically occur in the environment of matrix lamp bank displays, and particularly to accommodate the generation of heat by lamp energization.
The above objects have been accomplished by two different embodiments of the invention, which are disclosed in detail. One larger embodiment, adapted specifically for exterior display installations, utilizes a separable lens and supporting frame. The second embodiment, designed for smaller indoor installations, utilizes a lens and frame which are integrally molded. In both embodiments, the lens is positioned along an inclined plane that minimizes reflective glare from sunlight or adjacent ceiling light sources. In both embodiments there is provision for ventilation of the lens to permit heat to escape from about the light source located behind it. Both embodiments permit removal and installation of individual light filtering assemblies for initial manufacturing purposes, as well as field repairs and lamp replacement. These features will be more evident from the detailed disclosure that follows.